Monoglycerides used widely as surfactants and the like in cosmetics, foods, and industrial emulsifiers or lubricants are produced by esterification reaction of glycerin with fatty acid or by ester exchange reaction of glycerin with fat and oil. These reactions are carried out in the absence or presence of a catalyst, and generally a mixture of glycerin, monoglyceride, diglyceride and triglyceride is formed. The reaction system is usually a heterogeneous system, and the amount of monoglycerides formed is influenced by the solubility of glycerin in a fatty acid phase or a formed ester phase, and thus even if the amount of glycerin charged is merely increased, the content of monoglyceride cannot be increased. Accordingly, when higher performance (that is, high-purity) monoglycerides are to be obtained, purification by molecular distillation is carried out.
U.S. Pat Nos. 2,474,740 and 2,478,354 disclose a method of accelerating the ester exchange reaction of 5 to 15% water-containing glycerin with fat and oil in the absence of a catalyst.
U.S. Pat. No. 2,206,167 discloses a process for producing monoglycerides from glycerin and fats and oils by ester exchange reaction using an alkali (Na etc.) soap as a catalyst.
U.S. Pat. No. 2,628,967 discloses a process for producing monoglycerides by reacting glycerin or ethylene glycol with fatty acid or glycerin polyester at high temperatures in the presence of a specific transition metal (iron etc.) catalyst.